DIAMOND AND CARBONADO WASHINGS IN BRAZIL. 2l7 



to the surface the soil is of a dark red color and of a tallowy con- 

 sistenc}'. This soil is preferred by the few jDlanters of the region in 

 spite of its being deficient in running water, which, as is usual in 

 limestone regions, sinks through the fractures and caverns that 

 abound in the rock. 



The falls of the Paraguassu Eiver, formed by the rocks of this 

 region, yield diamonds and carbonados which are obtained by diving, 

 but it is uncertain whether these stones are derived from the rocks 

 belonging to this region or are brought down from the region above. 



Nothing is known of any other minerals of economic importance 

 with the exception of the limestone which has been used at many 

 places for the making of lime. 



It seems that the sandstone and limestone formation, which char- 

 acterizes a zone of some tens of kilometers in width along the eastern 

 base of the Serra das Lavras, extends toward the north and makes 

 up a large part of the so-called Matto do Urobo and also toward the 

 south in the limestone region of Brejo Grande. From an agricultural 

 point of view this zone is probably the most promising of the central 

 interior of the State of Bahia. 



The third region is made up of gneissic rocks abundantly cut by 

 plutonic eruptions apparently of the granitic type. Its lowest por- 

 tions are between 200 and 300 meters above sea level. In view of its 

 geologic constitution the extent of the relatively horizontal surface 

 features along the river and railway is rather striking. Above the 

 comparatively low and flat base rise hills and peaks to an elevation 

 of 800 meters and more. The low parts along the railway are cov- 

 ered with characteristic vegetation called " satinga," but it seems 

 that the more elevated portions are covered by forests and have the 

 reputation of being fertile. The rapid passage of the writer through 

 this zone upon the railway did not permit observations upon its 

 agricultural capabilities or mineral resources, but at several places 

 it was possible to note that the soil is thin even in flat places where a 

 greater thiclmess was to have been expected, and that many of the 

 granite hills were almost completely barren of vegetation. So far 

 as can be judged from its geologic constitution it is to be expected 

 that there are in places deposits of manganese, iron, graphite, and 

 perhaps other minerals of economic value. 



The fourth region is made up of beds of the soft sandstone of 

 Cretaceous and Tertiary ages that characterize the Reconcavo regions 

 of Bahia and offers but little of interest in the present study. 



The diamonds (including in this term the carbonados which rarely 

 if ever fail to accompany the true diamonds in the Bahia Chapada) 

 are especially characteristic of the first region, while their sporadic 

 occurrence in the second and third regions may plausibly be attrib- 



